This technical note outlines the design of an external seismic pre-isolation system proposed for use in LIGO Livingston. The goal is to reduce the effects of the site’s excess ground noise in the 1 3 Hz frequency band, allowing detector noise performance equivalent to that of the 4 km LIGO Hanford detector. The center histogram in Figure 8 shows the most troubling aspect of the excess noise qui...

Analytical seismic response of multi-story building supported on base isolation system is investigated under real earthquake motion. The superstructure is idealized as a shear type flexible building with lateral degree-of-freedom at each floor. The force-deformation behaviour of the isolation system is modelled by the bi-linear behaviour which can be effectively used to model all isolation syst...

In this study, the effect of deep excavation on the seismic response of RC moment resisting building systems has been studied. Deep excavation can cause significant changes in the stress and strain levels of soil environment and also changes in the propagation of seismic waves. This leads to permanent displacements in the foundation system. In this study, three RC building systems, i.e. 5, 10, ...

A seismic isolation system for the proposed 'Advanced LIGO' detector upgrade is under development. It consists of a two-stage in-vacuum active isolation platform that is supported by an external hydraulic actuation stage. A full-scale preliminary-design technology demonstrator of the in-vacuum platform has been assembled and is being tested at Stanford's engineering test facility. Unanticipated...

The seismic design of bridge structure is influenced by the bi-directional excitation phenomenon. The bi-directional effects have been ignored in most of the past studies. The calculation of maximum isolator displacements (as per the equation prescribed by AASHTO) also ignores the bi-directional effects of ground motion. In the formulation, the coupled behaviour of the isolation systems has als...

Buckling-Restrained Braced Frame system(BRBFs) are a new type of steel seismic-load-resisting system that has found use in several countries because of its efficiency and its promise of seismic performance far superior to that of conventional braced frames. The system is addressed in the 2005 edition of the AISC Seismic Provisions for Structural Steel Buildings, also a set of design provisions ...